Establishment of a Selective Liver Lobe Tumor-Bearing Mouse Model of Colorectal Cancer

PURPOSE

Colorectal cancer is one of the most common causes of cancer-related death, and its main site of metastasis is the liver. The surgical method used for metastases of colorectal cancer in the liver varies according to the lobe affected, as does the prognosis. However, there is a lack of relevant basic research. Therefore, a good animal model is needed for basic studies of metastases from colorectal cancer to the different lobes of the liver.

METHODS

A CT26 colon cancer cell line transfected with a virus expressing green fluorescent protein was inoculated into BALB/C mice via the spleen. Tumor formation in the liver lobes was observed under a fluorescence microscope according to which portal vein branch was ligated and according to clamping time. The differential formation of metastatic lesions in the different lobes was then compared with physical anatomy. Serum samples were used to detect the changes in liver function postoperatively.

RESULTS

Ligation and resection of the spleen 1 min after injection of the CT26 cells and release of the vessel clamp 1 min after splenectomy created an ideal tumor-bearing mouse model with little effect on liver function. Selective clamping of each portal vein branch and splenic injection of a CT26 cell line successfully established a selective liver lobe tumor-bearing model of colorectal cancer with distinct characteristics.

CONCLUSION

This model provides an opportunity for investigation of the mechanisms of metastasis of colorectal cancer to different lobes of the liver and may provide a basis for clinical treatment.

The Role of Farnesoid X Receptor in Accelerated Liver Regeneration in Rats Subjected to ALPPS

Background: the role of bile acid (BA)-induced farnesoid X receptor (Fxr) signaling in liver regeneration following associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) was investigated in a rat model. Methods: Male Wistar rats underwent portal vein ligation (PVL) (n = 30) or ALPPS (n = 30). Animals were sacrificed pre-operatively and at 24, 48, 72, or 168 h after intervention. Regeneration rate, Ki67 index, hemodynamic changes in the hepatic circulation, and BA levels were assessed. Transcriptome analysis of molecular regulators involved in the Fxr signaling pathway, BA transport, and BA production was performed. Results: ALLPS induced more extensive liver regeneration (p < 0.001) and elevation of systemic and portal BA levels (p < 0.05) than PVL. The mRNA levels of proteins participating in hepatic Fxr signaling were comparable between the intervention groups. More profound activation of the intestinal Fxr pathway was observed 24 h after ALPPS compared to PVL. Conclusion: Our study elaborates on a possible linkage between BA-induced Fxr signaling and accelerated liver regeneration induced by ALPPS in rats. ALPPS could trigger liver regeneration via intestinal Fxr signaling cascades instead of hepatic Fxr signaling, thereby deviating from the mechanism of BA-mediated regeneration following one-stage hepatectomy.

The effects of physical prehabilitation: Improved liver regeneration and mitochondrial function after ALPPS operation in a rodent model

BACKGROUND

To identify the role of physical prehabilitation (PP) in liver regeneration, mitochondrial function, biogenesis, and inflammatory response was investigated after associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) in a rodent model.

METHODS

Male Wistar rats (n = 60) underwent ALPPS. Animals were divided (n = 30) to the physical prehabilitation group (PP) and sedentary group (S). The animals were exsanguinated before (0 hour) and 24, 48, 72, or 168 hours after the operation. Regeneration rate and proliferation index were assessed. Mitochondrial function, biogenesis, and inflammatory response were evaluated.

RESULTS

Regeneration rate and Ki67 index were significantly increased in the PP group compared to the S group (P < .001). Due to the changes in oxidative capacity and ATP production rate, the P/O ratio of PP group compared to the S group was significantly increased (P < .05). PP group was characterized by accelerated mitochondrial biogenesis and less intense inflammatory response compared to the S group.

CONCLUSIONS

To our knowledge, this is the first demonstration of the beneficial effects of PP on liver regeneration, mitochondrial function, biogenesis, and the inflammatory response after ALPPS.

Laparoscopic left hemihepatectomy combined with right lateral hepatic lobectomy in pigs: surgical approach and comparative study of the inflammatory response versus open surgery

This study describes a left hemihepatectomy combined with a right lateral hepatic lobectomy. It compares the inflammatory response associated with laparoscopic hepatectomy (LH group, n = 7) with conventional open hepatectomy (OH group, n = 7). Blood was collected before surgery as well as 1, 2, 3, 5, and 7 days after surgery to determine the white blood cell count and levels of serum cortisol (COR), interleukin-6 (IL-6), and C-reactive protein (CRP). The left hemi-hepatectomy combined with a right lateral hepatic lobectomy was completed in miniature pigs. The average operative time was 139.00 ± 9.07 min, which was longer than that in the OH group (121.67 ± 3.02 min). The length of surgical incision associated with the OH group was 17.93 ± 1.09 cm, significantly longer than that related to the LH group (5.10 ± 0.17 cm). The estimated mean blood loss in the LH group was 136.43 ± 63.24 mL, which was significantly lower than that in the OH group. No severe complications (e.g., massive bleeding, bile leakage, and air embolism) were reported. The CRP levels, COR, and IL-6, increased significantly in the OH group and then slowly returned to their preoperative levels. A postoperative laparoscopic exploration revealed that the incised portion of the liver adhered to the omentum, but no additional abnormalities were observed. These findings indicate that a 4-trocar method for laparoscopic left hemihepatectomy combined with a right lateral hepatic lobectomy is safe and feasible. The inflammatory response for those receiving LH are lower than that for those receiving OH. This porcine model can be used as a research analog for liver disease and regeneration.

Associating liver partition and portal vein ligation for staged hepatectomy: establishment of an animal model with insufficient liver remnant

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) allows extended hepatectomy in patients with an extremely small future liver remnant (FLR). Current rodent models of ALPPS do not include resection resulting in insufficient-for-survival FLR, or they do incorporate liver mass reduction prior to ALPPS. Differences in FLR volume and surgical procedures could bias our understanding of physiological and hemodynamic mechanisms. We aimed to establish a rat ALPPS model with minimal FLR without prior parenchymal resection. In rodents, the left median lobe (LML) represents 10% of total liver. Partial hepatectomy (PHx) sparing LML and pericaval parenchyma represents our reference 87% resection. The first step in the procedure is either portal vein ligation (PVL) corresponding to ligation of all but the LML portal branches, or PVL with transection between the left and right median lobe segments (PVLT), and is defined as ALPPS stage-1. Second, ligated lobes were removed: PVL-PHx represents a conventional 2-stage hepatectomy, while PVLT followed by PHx is a strict reproduction of human ALPPS. In Group A, liver hypertrophy was analyzed after PVL (n = 38), PVLT (n = 47), T (n = 10), and sham (n = 10); In group B, mortality and FLR hypertrophy was assessed after PHx (n = 42), Sham-PHx (n = 6), PVL-PHx (n = 37), and PVLT-PHx (n = 45). In group A, PVLT induced rapid FLR hypertrophy compared to PVL (p < 0,05). Hepatocyte proliferation was higher in PVLT remnants (p < 0,05). In group B, PHx had a 5-day mortality rate of 84%. Sham operation prior to PHx did not improve survival (p = 0.23). In both groups, major fatalities occurred within 48 h after resection. PVL or PVLT prior to PHx reduced mortality to 33.3% (p = 0,007) or 25% (p = 0.0002) respectively, with no difference between the 2 two-stage procedures (p = 0.6). 7-day FLR hypertrophy was higher after the PVLT-PHx compared to PVL-PHx and PHx (p = 0.024). Our model reproduces human ALPPS with FLR that is insufficient for survival without liver resection prior to the stage-1 procedure. It offers an appropriate model for analyzing the mechanisms driving survival rescue and increased hypertrophy.

NAFLD Induction Delays Postoperative Liver Regeneration of ALPPS in Rats

BACKGROUND

Associating liver partition and portal vein ligation (ALPPS) is a promising two-step hepatectomy that is beneficial for accumulative regeneration of the future liver remnant (FLR) and avoids postoperative liver failure.

AIMS

Our study aimed to evaluate whether nonalcoholic fatty liver disease affected the liver regeneration induced by ALPPS.

METHODS

Sprague-Dawley rats fed a high-fat diet were used to construct the NAFLD model. ALPPS were performed, and blood and future liver remnant samples were collected at postoperative days 1 (POD1), POD3, and POD7.

RESULTS

The hepatic regeneration rate (HRR) of ALPPS was higher than that of portal vein ligation (PVL) at POD3 and POD7 (p < 0.05), and the number of Ki-67-positive hepatocytes (POD3) and CD68-positive Kupffer cells (POD7) per visual field was higher in the ALPPS group than in the PVL group (p < 0.05). The serum TNF-α, hepatocyte growth factor protein, and the serum IL-6 level were higher in the ALPPS group than in the PVL group at POD3 and POD7. Compared with those of the standard laboratory diet (SLD)-fed rats, the rats with NAFLD exhibited a decrease in the HRR, Ki-67-positive hepatocytes, and CD68-positive Kupffer cells in the FLR. The number of CD68-positive Kupffer cells was lower in rats with NAFLD than that in SLD-fed rats; noteworthily, the serum level of IL-6 and TNF-α changed dramatically after surgeries.

CONCLUSIONS

NAFLD induction delayed liver regeneration induced by the ALPPS procedure, which might be associated with hepatocyte proliferation and the number of Kupffer cells.

Mitochondrial function after associating liver partition and portal vein ligation for staged hepatectomy in an experimental model

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage strategy to induce rapid regeneration of the remnant liver. The technique has been associated with high mortality and morbidity rates. This study aimed to evaluate mitochondrial function, biogenesis and morphology during ALPPS-induced liver regeneration.

METHODS

Male Wistar rats (n = 100) underwent portal vein ligation (PVL) or ALPPS. The animals were killed at 0 h (without operation), and 24, 48, 72 or 168 h after intervention. Regeneration rate and proliferation index were assessed. Mitochondrial oxygen consumption and adenosine 5'-triphosphate (ATP) production were measured. Mitochondrial biogenesis was evaluated by protein level measurements of peroxisome proliferator-activated receptor γ co-activator (PGC) 1-α, nuclear respiratory factor (NRF) 1 and 2, and mitochondrial transcription factor α. Mitochondrial morphology was evaluated by electron microscopy.

RESULTS

Regeneration rate and Ki-67 index were significantly raised in the ALPPS group compared with the PVL group (regeneration rate at 168 h: mean(s.d.) 291·2(21·4) versus 245·1(13·8) per cent, P < 0·001; Ki-67 index at 24 h: 86·9(4·6) versus 66·2(4·9) per cent, P < 0·001). In the ALPPS group, mitochondrial function was impaired 48 h after the intervention compared with that in the PVL group (induced ATP production); (complex I: 361·9(72·3) versus 629·7(165·8) nmol per min per mg, P = 0·038; complex II: 517·5(48·8) versus 794·8(170·4) nmol per min per mg, P = 0·044). Markers of mitochondrial biogenesis were significantly lower 48 and 72 h after ALPPS compared with PVL (PGC1-α at 48 h: 0·61-fold decrease, P = 0·045; NRF1 at 48 h: 0·48-fold decrease, P = 0·028). Mitochondrial size decreased significantly after ALPPS (0·26(0·05) versus 0·40(0·07) μm² ; P = 0·034).

CONCLUSION

Impaired mitochondrial function and biogenesis, along with the rapid energy-demanding cell proliferation, may cause hepatocyte dysfunction after ALPPS. Surgical relevance Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a well known surgical strategy that combines liver partition and portal vein ligation. This method induces immense regeneration in the future liver remnant. The rapid volume increase is of benefit for resectability, but the mortality and morbidity rates of ALPPS are strikingly high. Moreover, lagging functional recovery of the remnant liver has been reported recently. In this translational study, ALPPS caused an overwhelming inflammatory response that interfered with the peroxisome proliferator-activated receptor γ co-activator 1-α-coordinated, stress-induced, mitochondrial biogenesis pathway. This resulted in the accumulation of immature and malfunctioning mitochondria in hepatocytes during the early phase of liver regeneration (bioenergetic destabilization). These findings might explain some of the high morbidity if confirmed in patients.

Study of liver in HBV-related hepatocellular carcinoma: Stereology shows quantitative differences in liver structure

Hepatocellular carcinoma is one of the main consequences of liver chronic disease. Hepatocellular carcinoma-related changes may be seen in patients with chronic hepatitis B. The aim of the current study was to quantitate liver tissue elements by stereological technique in patients with hepatitis B-related cancer and compare the results with control and only hepatitis B group. Needle liver biopsies from 40 patients with only chronic hepatitis B infection, from 41 patients with only early hepatocellular carcinoma, from 40 patients with early hepatitis B-related cancer and 30 healthy subjects (control group) were analyzed by stereological method using systematic uniform random sampling method. Haematoxylin and eosin stained sections were used. The numerical density of hepatocytes, hepatocyte volume, numerical density of Kupffer cells, volume density of the connective tissue in the portal space, and volume density of the connective tissue were assessed. Quantitative analysis of liver samples indicated that there were statistically significant differences in the numerical density of hepatocytes, hepatocyte volume, numerical density of Kupffer cells, volume density of the connective tissue in the portal space, and volume density of the connective tissue between control and hepatitis B-related cancer and hepatitis B groups. Quantitative, stereological technique is simple and reliable for evaluating HCC in chronic hepatitis B. It is useful for assessing the liver tissue parameters. Stereology is recommended for the diagnosis of people prone to cancer in patients with chronic hepatitis B.

Distribution of Connective Tissue in the Male and Female Porcine Liver: Histological Mapping and Recommendations for Sampling

The pig is a large animal model that is often used in experimental medicine. The aim of this study was to assess, in normal pig livers, sexual dimorphism in the normal fraction of hepatic interlobular and intralobular connective tissue (CT) in six hepatic lobes and in three macroscopical regions of interest (ROIs) with different positions relative to the liver vasculature. Using stereological point grids, the fractions of CT were quantified in histological sections stained with aniline blue and nuclear fast red. Samples (415 tissue blocks) were collected from healthy piglets, representing paracaval, paraportal and peripheral ROIs. There was considerable variability in the CT fraction at all sampling levels. In males the mean fraction of interlobular CT was 4.7 ± 2.4% (mean ± SD) and ranged from 0% to 11.4%. In females the mean fraction of the interlobular CT was 3.6 ± 2.2% and ranged from 0% to 12.3%. The mean fraction of intralobular (perisinusoidal summed with pericentral) CT was <0.2% in both sexes. The interlobular CT represented >99.8% of the total hepatic CT and the fractions were highly correlated (Spearman r = 0.998, P <0.05). The smallest CT fraction was observed in the left medial lobe and in the paracaval ROI and the largest CT fraction was detected in the quadrate lobe and in the peripheral ROI. For planning experiments involving the histological quantification of liver fibrosis and requiring comparison between the liver lobes, these data facilitate the power analysis for sample size needed to detect the expected relative increase or decrease in the fraction of CT.

Role of Kupffer cells in the progression of CRC liver metastases after the first stage of ALPPS

Associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been suggested as a potential therapy for extensive bilobar liver tumors, although in some circumstances this technique may induce tumor progression, a fact still not well studied. Our aim was to study tumor hepatic progression induced by the first step of ALPPS in a WAG/Rij rat syngenic model of metastatic colorectal carcinoma by subcapsular CC531 cell line inoculation. ALPPS induced: tumor progression on deportalized lobe and metastases; expression of hepatic vasculogenic factors (HIF1-α and VEGF); and a dramatic increase of Kupffer cells (KCs) and tumor-associated macrophages (TAMs). Interestingly, KCs expressed COX-2 (M1 polarization), while TAMs expressed mainly arginase-1 (M2 polarization). ALPPS also induced a decrease of tumor-infiltrating lymphocytes and an increase of intrahepatic T lymphocytes. Thus, ALPPS technique seems to induce a hypoxic environment, which enhances hepatic HIF1-α and VEGF expression and may promote KCs and TAMs polarization. Consequently, the regenerative stimulus seems to be driven by a pro-inflammatory and hypoxic environment, in which M1 intrahepatic macrophages expressing COX-2 and T-Lymphocytes play a key role, facts which may be related with the tumor progression observed.

Liver regeneration during the associating liver partition and portal vein ligation for staged hepatectomy procedure in Sus scrofa is positively modulated by stem cells

This present study investigated the impact of the application of stem cells to liver regeneration following the first stage of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). The experiment was conducted on a pig model (n=6, 3 that did not receive application of stem cells, 3 that received application stem cells). Collected samples of liver (day 0 and 9 following surgery) were subjected to complete transcriptome sequencing. In total, 39 differentially expressed genes were found in the group without the application of the stem cells (genes of unwanted processes such as fibrosis and inflammation). In the group that did receive application of stem cells, no significantly differentially expressed genes were found, indicating a properly regenerated liver remnant. The present study therefore demonstrated, to the best of our knowledge for the first time, the positive effect of stem cells application in the liver regeneration process during ALPPS procedure in the pig model.

Rapid Liver Hypertrophy After Portal Vein Occlusion Correlates with the Degree of Collateralization Between Lobes-a Study in Pigs

BACKGROUND

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) induces more rapid liver growth than portal vein ligation (PVL). Transection of parenchyma in ALPPS may prevent the formation of collaterals between lobes. The aim of this study was to determine if abrogating the formation of collaterals through parenchymal transection impacted growth rate.

METHODS

Twelve Yorkshire Landrace pigs were randomized to undergo ALPPS, PVL, or "partial ALPPS" by varying degrees of parenchymal transection. Hepatic volume was measured after 7 days. Portal blood flow and pressure were measured. Portal vein collaterals were examined from epoxy casts.

RESULTS

PVL, ALPPS, and partial ALPPS led to volume increases of the RLL by 15.5% (range 3-22), 64% (range 45-76), and 32% (range 18-77), respectively, with significant differences between PVL and ALPPS/partial ALPPS (p < 0.05). In PVL and partial ALPPS, substantial new portal vein collaterals were found. The number of collaterals correlated inversely with the growth rate (p = 0.039). Portal vein pressure was elevated in all models after ligation suggesting hyperflow to the portal vein-supplied lobe (p < 0.05).

CONCLUSIONS

These data suggest that liver hypertrophy following PVL is inversely proportional to the development of collaterals. Hypertrophy after ALPPS is likely more rapid due to reduction of collaterals through transection.

Experimental evaluation of liver regeneration patterns and liver function following ALPPS

Background

The underlying mechanism of liver regeneration after Associating Liver Partition and Portal vein ligation (PVL) for Staged hepatectomy (ALPPS) is still unclear. The aim of this study was to evaluate the relationship between future liver remnant (FLR) volume, liver regeneration characteristics and restoration of function in an experimental model of ALPPS.

Methods

An ALPPS model in rats was developed with selective PVL, parenchymal transection and partial hepatectomy (step 1), followed by resection of the liver (step 2). Three different ALPPS groups with FLR sizes of 30, 20 and 10 per cent of total liver volume were compared with sham‐operated controls and animals undergoing resection of left lateral lobe and 90 per cent PVL with respect to morbidity, mortality, liver regeneration and function.

Results

Three of 15 animals that had ALPPS with 10 per cent FLR (ALPPS10) died after step 1. Ascites developed in two of five rats that had ALPPS with 20 per cent FLR and in three of four animals in the ALPPS10 group after step 2. Although the relative increments in FLR size and growth rates were highest in the ALPPS groups, small FLR size was associated with a sustained increase in levels of serum aminotransferases and bilirubin, a lower albumin concentration, severe sinusoidal injury, increased expression of proliferation markers and increased activation of hepatic progenitor cells after step 2.

Conclusion

There is discordance between FLR volume increase and functional restoration after the ALPPS procedure.